My take on the recent ‘high protein diet as bad a smoking’ study

There are reports of a study doing the round in the UK press this week that warn us that eating a protein-rich diet is ‘as bad for us a smoking’. See here and here for examples of stories appearing in the ‘respected’ broadsheets the Telegraph and Guardian respectively. Reading the headlines of these pieces gives the distinct impression, I think, that low-carb and ‘paleo’ eating puts people on a fast-track to an early demise, particularly from cancer and diabetes. Given my nutritional stance (generally pro-low-carb and pro-paleo), perhaps not surprisingly, I’ve had quite a few emails asking for my opinion on this research.

The study concerned involved asking people to log what they ate over the course of a day, and then following them over a period of about 18 years. This type of research is ‘epidemiological’ in nature, which means it looks at associations between things. This study found an association between higher animal protein intakes and increased risk of death from diabetes, cancer and death overall in individuals aged 50-65. However, just because such a link was found, does not mean it’s protein that is causing the apparently harmful effects.

It might be, for example, that individuals who eat a lot of animal protein might also smoke more, and this is the real explanation for the link between animal protein and increased risk of death. Researchers can ‘control’ for these other factors (called ‘confounding factors’), and this was the case in this study. However, this process is far from perfect, and still leaves us with data that can only ever show associations (and not causality).

It is perhaps worth bearing in mind that this was a relatively small study. But would a larger study have been better? Or multiple studies showing the same thing? The reality is that epidemiological evidence is limited in its power by the very nature of this research, and having bigger or more studies does not magically transform a sow’s ear into a silk purse.

Imagine a study that finds a correlation between ice cream sales and shark attacks. One can imagine that more ice cream is sold when the weather is warm, and more people are likely to end up in the sea when the weather is warm too. However, the idea that ice cream actually causes shark attacks is probably incorrect, right? And it doesn’t matter if you have a mammoth study or 20 similar studies showing such an association, the fact is ice cream still doesn’t cause shark attacks.

This inherent weakness of epidemiological studies is the major reason why, these days, I hardly ever write about or comment on this sort of research. If it wasn’t for the fact that this recent study has had so much attention and me so many emails about it, I wouldn’t be writing about it at all.

The way the study has been reported, though, is not nearly as circumspect as it should have been, I think. We can lay the blame at the feet of the ‘science’ journalists who have reported this study in what might be termed a ‘sensationalist’ way. But, likening protein-rich diets to smoking appears to have come from one of the study authors: Dr Valter Longo is quoted in the Telegraph as saying:

We provide convincing evidence that a high-protein diet – particularly if the proteins are derived from animals – is nearly as bad a smoking for your health.

I have news for Dr Longo: No he hasn’t.

But there’s another part of this ‘research’ that appears to have been lost in translation. In individuals aged 66 or older, high protein diets were found to be associated with a lower risk of death overall, including a reduced risk of death from cancer. According to the authors of this study, it seems that somewhere around our mid-60s our protein needs flip from low to high. If this sounds faintly ridiculous to you, then that’s because it is (I think).

Crucially, when all individuals over the age of 50 were considered, no relationship was found between protein intakes and risk of death or risk of death from cancer. This, I would say, is the bottom line of this study, but it’s got completely buried in the ‘Atkins gives you cancer’ rhetoric.

Interestingly, this overall result was the first result to be reported by the authors in the study, and my suspicion is that their original intention was to perhaps find something meaningful here and leave it at that. However (and this is idle speculation on my part), it seems that after finding nothing, they decided to see what ‘meaningful’ results they could dredge from the data. In scientific parlance, this is referred to as ‘post-hoc analysis’. A colloquial way to describe it is ‘shifting the goalposts’.

The end result is that a weak study showing nothing much gets interpreted in a way that I believe is sensationalist, over-hyped and misleading. The problem here is that it might lead many to doubt the appropriateness of how they are eating and lead them to a diet that is altogether less healthy (such as one rammed full of carbohydrate).

Researchers and scientists have a responsibility to report their findings accurately and honestly. I’m not sure Dr Longo has done that here, at all. Likening protein-rich diets to smoking on the basis of epidemiological evidence is not only unscientific but potentially damaging. I wonder whether Dr Longo will reflect on his soundbite and wonder whether he might have (even unwittingly) put headlines in front of public health.

References:

1. Levine ME, et al. Low Protein Intake Is Associated with a Major Reduction in IGF-1, Cancer, and Overall Mortality in the 65 and Younger but Not Older Population. Cell Metabolism. 2014;19(3):407-417

57 Responses to My take on the recent ‘high protein diet as bad a smoking’ study

As Zoe Harcombe points out “Dr Longo, has declared interests in (actually, he’s the founder of) L-Nutra – a company that makes ProLon™ – an entirely plant based meal replacement product.” Another case of ‘follow the money’

erm, Dr. Briffa, you’ve missed out on the fact that what they are calling a high-protein diet isn’t really one. It’s just a typical western high-carb diet that just has a very slight amount more protein in it that what they’re calling a low-protein diet.

It’s very disingenuous to call something high-protein when there’s 50% carbs in it…

That’s about what I thought. They never control for carb intake on studies like this.

Something else they never seem to tease out is that because most people believe animal protein’s unhealthy, people who deliberately abstain from animal protein or deliberately eat less of it are also more likely to pursue behaviors considered healthy, such as taking up exercise or quitting smoking. Whereas a dedicated meat-eater, especially a dedicated red-meat-eater, is more likely to resent attempts at micromanaging what they eat and how or whether they pursue better health, and continue doing whatever they want without thought to the outcome.

I’m also having a hell of a lot of trouble believing that they got ALL these study participants to fill out an ACCURATE questionnaire EVERY DAY from age 18 onward for years and years and years. Just not buying it.

I agree. This ridiculous pseudo science makes me angry especially because newspapers pay such attention to it. It is more likely that the group had more cancer and diabetes because they consumed more starch and sugar.

That’s about what I thought. They never control for carb intake on studies like this.

Something else they never seem to tease out is that because most people believe animal protein’s unhealthy, people who deliberately abstain from animal protein or deliberately eat less of it are also more likely to pursue behaviors considered healthy, such as taking up exercise or quitting smoking. Whereas a dedicated meat-eater, especially a dedicated red-meat-eater, is more likely to resent attempts at micromanaging what they eat and how or whether they pursue better health, and continue doing whatever they want without thought to the outcome.

I’m also having a hell of a lot of trouble believing that they got ALL these study participants to fill out an ACCURATE questionnaire EVERY DAY from age 18 onward for years and years and years. Just not buying it.

They did control for carbohydrate but I think that we make a mistake in trying to explain the results as if they were statistically sound and we need to see how they went wrong. I am not a statistician but statistics is not science. It is a series of methods which have to be applied appropriately. This study produces meaningless numbers. They don’t have to be explained. We need to bring out how the wrong analysis was done. Not easy especially when you have a hard-nosed, truculent character like Longo.

I tell my patients that when they reach 90 they can start smoking drinking to excess and having unprotected sex! Seriously, when you reach a certain age these lifestyle factors likely decrease in potency.

Maybe eating American grain fed beef and dairy does increase the risk. How much Omega 6 linoleic acid, an established risk factor, is consumed from both the meat itself and the oil used for cooking? This sort of “research” using whole “foods” originating from America is worthless. Do these journals never peer review research prior to publication?

The most ridiculous part of this study, in my opinion, is that the data set was from a single 24-hour dietary recall survey and nurse-performed measurements for things like BMI, BP, etc. 18 years ago. To claim that this one day’s eating represents a lifetime eating habit beggars belief. They should have claimed “People who had that one heavy protein day 18 years ago got cancer at a higher rate…” It’s certainly more accurate.

It was hardly a ‘high-protein’ diet – see this from the NHS link above:

“n this study, on average people ate 51% of their calories in the form of carbohydrates, 33% as fat and 16% as protein (11% animal protein). This is likely to be higher in fat and lower in carbohydrates than that recommended on the “Eatwell Plate” which shows the relative proportions of food that we should aim to eat.”

It says in the Guardian that “People who took part in the study consumed an average of 1,823 calories a day, with 51% coming from carbohydrates, 33% from fat, and 16% from protein, of which two thirds was animal protein.”

From observation: people everywhere are better nourished and healthier than ever before; in Western Countries people are living longer.

Then main risk factor for disease is genetic; to lower risk people, should change their parents not diet or lifestyle.

Absurd?

Anymore so than the endless ‘research’ and comical, hyperventilating media reports or willingness of politicians to believe whatever an ‘expert’ says no matter that ‘experts’ have been qrong every time whether about population explosion, new ice age/global warming or the economy?

I keep asking myself why the medical profession, ie those not affiliated to a commercial body, do not stand up to these people publicly and in the very press that publishes this rubbish? And then I realise that time is running out for free speech in the medical profession as soon they will all be working for the profit motive with little incentive for independent research at any level. You can’t be on your own here, John? I really fear for my grandchildren. They should be our incentive but I feel so powerless. We need a campaign to ensure that the press give proper opportunity for rebuttal to such bad science. I see that the NHS choices critique of Lango’s piece is highly critical but is this getting publicity? Time for another radio interview, John? Thank you for all your efforts.

Well, it’s all down to the Emperor’s New Clothes, isn’t it. Nobody is going to ‘fess up’ any time soon about disgusting margarines awash with omega6 and other unwholesome poor quality foodstuffs we are constantly being told we must eat “for the good of our health” or for the overprescribing of statins, also ‘for the good of our health’. An awful lot of scientists, doctors, nutritionists – most of the medical profession probably, etc. would risk total loss of face.
What could they say? “Sorry people, we think we ought to tell you that we made a bit of a mistake – we’ve made you fat and sick. Oops”
Grrrrr.

I am not that surprised at the association found. There is also a very strong association between dairy intake and certain types of common cancers (e.g. breast and prostate), so this fits. It may be that the growth factors and increased hormone production are to blame, with some carcinogenic compounds also in meats, particularly processed meats. As you get older these growth/hormone factors may become less important as your body may actually benefit, on balance, hence the associations found. Speculation I know, and proper research needs to be done on this (the dairy industry will not like that). The thing about epidemiological associations is that it helps to identify areas of potential causality that should be researched more thoroughly.

Thanks John. I’m glad that the NHSChoices website has also given a balanced response. By the way, do you have a visual representation of the Eatwell Plate they refer to on NHS Choices? It would be useful to be able to share this with patients.

Let’s not throw the baby out with the bathwater though… protein and IGF-1 is an issue. My personal needs for protein appear to be a bit higher than the 1g to 1Kg of lean bodyweight, but I do have to keep in mind that the more protein I take in, the more careful I have to be as ‘too much’ isn’t a good thing. Unfortunately, I haven’t been able to find anything that will reliably predict what is too much for my organism. I expect we’ll know when I die

Towards the end of a Guardian piece by Zoe Williams on the subject in G2 she writes the following:

“But the overriding fact in all this is that this new study is wrong: the US data set from which it is drawn is fatally flawed and the link between protein and premature death is simply not demonstrable from this evidence. Jack Winkler, former professor of nutrition policy at Metropolitan University, explains: “They did a correlation between the national diet survey in the United States (NHANES), and some data on death by disease. They linked it up, then alleged that protein caused death. Now, NHANES suffers from what all diet surveys suffer, namely: you ask people what they eat and what you get back is lies. People respond normatively. They put themselves in the best possible light. They’re not harmful, deceitful lies. In the case of the British survey, people underreport how much they eat by 25% and adolescents by 30%. Underreporting they call it, but in plain English, it’s lies.”

A study has just been published on what’s wrong with NHANES, which concludes: “Across the 39-year history of the NHANES, EI [Employment Insurance] data on the majority of respondents (67.3% of women and 58.7% of men) was not physiologically plausible.” In plain English, if they really ate what they said they’d eaten, they would no longer be alive. In two-thirds of cases.

Winkler continues: “The practical consequence for the protein story is that you’ve got a correlation between food intake and disease, but the food intake data is so poor that any correlation is suspect. Academics sit in front of a computer screen and do data analysis. But they never question the quality of the primary data. I’m not being rude, but my attitude towards that study is contempt.”

So true – I read that article and had to read all the way to the end to see that. What came before though, was so tongue in cheek that I couldn’t tell if I was intended take this section of the article seriously or not.

Honestly, even on a low-carb diet, protein needs to be adequate and not excessive. A low-carb diet is a high-fat diet, with adequate protein, tons of veggies and some fruits. It is not a high-protein diet (you can read Protein Power by Dr. Michael Eades and he states how one get adequate amounts of protein, not excessive amounts). Since I do moderate low-carbing, anywhere from 50 grams to 150 grams in any given day, I don’t overdo protein in any case. On a very low-carb diet, people that eat huge amounts of protein, shoot themselves in the foot, as it turns into glucose in the body anyway, by a process called gluconeogenesis.

True – a low-carb diet doesn’t include excessive protein, but just what we need. I don’t really worry about how many grams I eat – I find it would be quite hard to overeat protein as there seems to be a natural limit to what I want.

Grass fed, organic meat and dairy, never hurt anyone. It is the quality of the protein that counts and most protein consumed by people today is dire, from sick, maltreated factory farmed animals, pumped full of antibiotics that never see the light of day. There is also an agenda here particularly for this Country, to destroy our farmers and farming.

Isn’t it a pity…….. the usual headline grabbing fiasco of the press!! Which unfortunately many will read and take as gospel. Thank heavens for steady, sound, provable advice such as Dr Briffa gives in both “Escape the Diet Trap” and “A Great Day at the Office”. People need to stop jumping on bandwagons and find out for themselves what works and what doesn’t. And what doesn’t work is swapping horses mid-race, fad diets and slimming clubs!!! Read these two books. Act on the advice (with support from your GP obviously if necessary before embarking) and look on it as a long-term health investment ……. not a short term fix.

One of the problems, if not the greatest, is the idea that there is some kind of “gold standard” for research, that is, one kind of an experiment, like the RCT, that fits all problems. This idea is completely unknown in the physical sciences. You do what it takes to answer the question. You don’t need an RCT to show that penicillin is effective against gram positive infections. You may want to do one to demonstrate safety since it is a foreign substance but that is a different question. It is not that the press is clueless. It is that they don’t care. There existence in sciencee reporting rests on the “breakthrough” and the scare story “why the peanut butter in your child’s lunch may cause him to go blind.” If there is a single word that has hurt health care most in the world it is “may.”

Richard–I agree. Empirical observations often show us where to aim our guns when we do perform RCTs. After all, do you really want to spend a lot of time and money studying sideways falling apples?

What I find absurd about this study is that they focus on diabetes mortality. They followed over 83,000 people over the age of 50 for 18 years. Their dietary intake was based on a 25-hour recall survey done at the beginning of the study. After 18 years there was 40% mortality but diabetes mortality was only 1%–a total of 21 deaths.

Thus it seems highly unlikely that anything meaningful can be concluded based on these numbers.

In agreement with some of your respondents that the quantity of protein is not the issue. It’s rather the confounding toxins and overabundance of inflammatory omega-6 in factory farm food that makes some protein harmful. Organic, grass-fed, pasture-raised animal products are full of healthy nutrients. See my article on Bulgarian yogurt as an example of healthy dairy (http://thescienceofnutritiondotnet.wordpress.com/2014/02/13/health-benefits-of-bulgarian-yogurt/). It boils down to quality, and we must learn to make those distinctions before we go around scaring people.

For some years prior to 1974 frequently I was hyper (often aggressively) when I would feel a tad under the weather. My late wife observed that my personality altered whenever I had a meal containing meat (this could have been connected to how the animals were then fed). As an experiment I stopped eating meat or anything containing meat and within four days felt a distinct improvement and after ten days felt really great when my behaviour became stable. Subsequently I became a vegetarian with a diet that was high in carbs and vegetable oils but within three to four years began to suffer from the early symptoms of cardiac problems which was put down to ageing. Other health problems arose such as haemorrhoids and prostate enlargement with their consequential symptoms. Surgery brought about some relief but did not cure. During September 1990 I had to have a quadruple by-pass and on coming out of intensive care and being asked what I would like for breakfast my reply was, “If I am about to die then I am going to die happily so may I have streaky-bacon with eggs.” In the past twenty-three years since I have been on a high protein diet with lashings of saturated fat but low in vegetable oils, and at the age of 83, I remain in excellent health. The meat that I eat is predominantly from meadow-fed animals and the eggs from free-ranging hens. It also contains lots of carbs as I like my breads, cakes, pastries, pies, and biscuits but I avoid, where possible, baking made with poly or mono unsaturated fats. I stopped smoking aged thirty, stopped imbibing alcoholic beverages, aged 45, ceased drinking soft drinks about aged 60 (or earlier). I take almost no fruit as I am not fond of it and consume little vegetables although do occasionally take curly kale and pickled beetroot, two vegetables regarded as being highly nutritious. The beetroot controls symptoms of nocturnal cramp which has affected me in recent years. Today, from observation and experimentation over the past twenty years I find that saturated fat, both animal and vegetable, is bodily healthy and I am convinced that it is a buffer to ill-health.

When this anecdotal experience is compared to the findings of the research mentioned it might be appreciated if I express a jaundiced view of it.

“Here is your funky math as far as I can see it to how your group was able to “support” the conclusion of a 70% increased risk with data:

43 death out of 437 participants (9.8%) was calculated as 43/6381 or .007% (which was rounded to .01%)
480 deaths out of 4,798 participants (10.1%) was calculated as 480/6381 or .075%
103 deaths out of 1,146 participants (9.0%) was calculated as 103/6381 or .017% “

Good critique but one of the strangest things about all this epidemiologic stuff is that there really are standards for telling when association implies causality, the first of which is the strength of the effect. Bradford Hill, who showed the association between smoking and cancer laid these ideas out. The highest odds ratio (OR) found in this study was 3, but the OR for smokers and cancer was 10 and for heavy smokers was 20. Others included specificity, smokers were not at risk for all cancers. I described Hill’s criteria in a blogpost http://wp.me/p16vK0-gz and I also pointed out how restrained and reasonable Hill was — her recognized that common sense was most important. Interestingly, Walter Willett’s book on Nutritional Epidemiology which is a masterpiece in describing the practice and results in the field has no mention of Bradford Hill suggesting that Hill’s work on smoking may have been the last result in epidemiology that was useful. IMHO.

I have told you in the past, your summary on this topic is the best I have read to date. Science is messy and humans are even messier. You mix them together and you often end up with a real mess. Science put us on the moon and gave us the moon-shot of nutritional science–the Twinkie. Need I say more?

On the subject of epidemiological inferences, you might be interested in a quick critique I threw together based mostly on the extra data from the offending study that was not included in the final report:

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